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Brake piston tool

20K views 57 replies 18 participants last post by  KJW 
#1 ·
I have searched within the forum for exact information on winding back brake pistons and have found nothing so hopefully this will not get booted into the ether. I have purchased new discs and pads and have an mot coming up in 4 weeks. I am aware the pistons will need winding back in but for the life of me I cannot find/identify the tool and when you search online it is ALWAYS the XF that is referred to. Can someone answer the following questions if at all possible.
1. Where can I get the tool from or what does it even look like?
2. When winding back in is the near side clockwise/anti-clockwise
3. I know from this forum that you need to put the ignition into accessory mode to release the elctonic park brake but how long does it stay like that as if you sit there in the car in this mode without starting it shuts everything down after a few minutes and will cause mayhem if the rear discs are off at this point in time.
As warranties are coming to an end and more used XE's are sold there will be many people wanting to replace their brakes without having the vaseline treatment at the main dealers! I think we need a definitive 'how to' on this one. I will provide one if I can get the various bits of info needed along with step by step photos.
 
#52 ·
chrisjp said:
j.a.mcguire said:
Just to confirm, you do not need the piston winding tool to complete this job. Ensure the Electronic Parking Brake has been placed into Service Mode, take the lid off the brake fluid reservoir and then you can compress the brake piston back into the cylinder with minimal effort.

You probably don't want to use a g-clamp for this job as the brake caliper has a plastic housing on the back holding the electronics, so you'd probably end up crushing these with a regular g-clamp, this is where the rewind tool does come in handy, although it's not required, it operates inside the caliper housing and is perfectly shaped for the job.
Does anyone know if, instead of putting the parking brake into service mode, you can use the cable lever on top of the engine (under the plastic cover) used for towing which releases the parking brake and puts the transmission into neutral?
I ask because of reports of the service mode sometimes spontaneously reverting to normal mode. A physical cable seems much more secure than the sometimes erratic behaviour of JLR electronics!
Doesnt that just put the gearbox in park as there is a motor on each caliper, so no mechanical link to the caliper
 
#53 ·
Wolfie1 said:
chrisjp said:
j.a.mcguire said:
Just to confirm, you do not need the piston winding tool to complete this job. Ensure the Electronic Parking Brake has been placed into Service Mode, take the lid off the brake fluid reservoir and then you can compress the brake piston back into the cylinder with minimal effort.

You probably don't want to use a g-clamp for this job as the brake caliper has a plastic housing on the back holding the electronics, so you'd probably end up crushing these with a regular g-clamp, this is where the rewind tool does come in handy, although it's not required, it operates inside the caliper housing and is perfectly shaped for the job.
Does anyone know if, instead of putting the parking brake into service mode, you can use the cable lever on top of the engine (under the plastic cover) used for towing which releases the parking brake and puts the transmission into neutral?
I ask because of reports of the service mode sometimes spontaneously reverting to normal mode. A physical cable seems much more secure than the sometimes erratic behaviour of JLR electronics!
Doesnt that just put the gearbox in park as there is a motor on each caliper, so no mechanical link to the caliper
From what I remember of being recovered three times, once the gearbox is in neutral the parking brake can be released just by switching the ignition on and depressing the brake button and will stay off as long as the gearbox remains in neutral
 
#54 ·
Just to advise, i didn't understand the difference between the lever under the bonnet and the electronic parking brake either.

The lever under the bonnet is a direct mechanical link to the parking pawl which resides in the transmission and locks into the teeth on one of the gears, essentially placing the transmission in park and preventing the wheels from turning. When you pull the release lever under the bonnet it frees the pawl and puts the transmission into neutral allowing the wheels to turn freely.

The Electronic Parking Brake is idependant of this, and is electronically operated by the servos on the back of the brake calipers themselves. They still remain active and will continue to prevent the wheels moving even if the parking pawl is released on the transmission. So the EPB must be deactivated separately. This is done by placing the EPB into service mode.
 
#55 ·
j.a.mcguire said:
Just to advise, i didn't understand the difference between the lever under the bonnet and the electronic parking brake either.

The lever under the bonnet is a direct mechanical link to the parking pawl which resides in the transmission and locks into the teeth on one of the gears, essentially placing the transmission in park and preventing the wheels from turning. When you pull the release lever under the bonnet it frees the pawl and puts the transmission into neutral allowing the wheels to turn freely.

The Electronic Parking Brake is idependant of this, and is electronically operated by the servos on the back of the brake calipers themselves. They still remain active and will continue to prevent the wheels moving even if the parking pawl is released on the transmission. So the EPB must be deactivated separately. This is done by placing the EPB into service mode.
Not so…. I can assure you that Jag Assist (who recovered my car three times) simply released the parking brake using the switch, not by putting it in service mode
 
#56 ·
Indianajons said:
j.a.mcguire said:
Just to advise, i didn't understand the difference between the lever under the bonnet and the electronic parking brake either.

The lever under the bonnet is a direct mechanical link to the parking pawl which resides in the transmission and locks into the teeth on one of the gears, essentially placing the transmission in park and preventing the wheels from turning. When you pull the release lever under the bonnet it frees the pawl and puts the transmission into neutral allowing the wheels to turn freely.

The Electronic Parking Brake is idependant of this, and is electronically operated by the servos on the back of the brake calipers themselves. They still remain active and will continue to prevent the wheels moving even if the parking pawl is released on the transmission. So the EPB must be deactivated separately. This is done by placing the EPB into service mode.
Not so…. I can assure you that Jag Assist (who recovered my car three times) simply released the parking brake using the switch, not by putting it in service mode
Thank you all for this input.
I note that as well as using the mechanical link to release the parking pawl, it is also necessary to release the EPB, but that this can be done while the parking pawl is released via the mechanical link by merely turning on the ignition and using the switch under the steering column to release the EPB. This makes sense because I can't imaging that a recovery vehicle operative would have the necessary knowledge to put the EPB into service mode.
However, if car is not started for a while after the the ignition is switched on, the ignition turns itself off again (presumably to stop battery drain). If this happens then won't the EPB reactivate? Or does releasing the parking pawl via the mechanical link somehow stop this automatic EPB reactivation?
 
#57 ·
Indianajons said:
Not so…. I can assure you that Jag Assist (who recovered my car three times) simply released the parking brake using the switch, not by putting it in service mode
Keeping the EPB deactivated for extended periods without using service mode is possible on the manual transmission only.

In the case of an automatic, you can only release the parking brake with the ignition on. With the ignition on and the engine not running such as when the vehicle is being transported or serviced, the ignition will eventually automatically turn off to save the battery. Once it does so, the EPB will apply automatically.

For vehicle recovery, the vehicle either needs to be fully supported on a flat-bed, or have the rear-axle lifted.
 
#58 ·
It's worth remembering that releasing the EPB so the car can be moved and putting it into service mode are two different things!

When servicing the brakes, you need to push the pistons fully back into the calipers and, to avoid damage to the parking brake mechanism, the parking brake needs to be fully retracted to achieve this. This only happens when in service mode. Releasing the EPB using the button just releases the EPB mechanism slightly from the "bite point" but not enough to fully retract the caliper piston. There's also the danger that the brake could be re-applied without warning in this state.

Exiting service mode also causes a recalibration of the "bit point" which is necessary when new pads have been fitted.
 
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